Izzy woes

[Brimfire]

My IZH-46M Izzy has been poorly for a while. It suffers from a rolling and intermittent combination of not cocking, compressing, leaking and drooping bolt block. I've never worked out whether it's got one overarching problem or a few minor ones in combination.

To start with, the bolt block doesn't go all the way back and engage the trigger sears as it once did unless I perform a violently fast outward stroke of the charging lever allowing the increased speed/momentum of the block to travel fully back and engage.

My suspicion is that the bolt bar, the rod connecting the slide latch to the bolt block, has an elongated hole which is losing an all important couple of mil travel at the end of its stroke.

The hole has some wear but it seems minimal. I've nothing to compare the size of the hole to so can I ask my fellow Izzy fans if if this looks normal please?

Another issue I'm having is, that with the bolt block thumbed back fully, I can get the Izzy to compress but, when I push the block back down, there's a hissing leak from the transfer port. It's most noticeable if done slowly but a fast pushdown of the block allows reasonably consistent shots in the 450fps range.

Anyone seen and repaired this fault before?

[Brimfire]

Recently, I got hold of another Izzy for comparison purposes.

The amount of movement allowed by the slot in the bolt bar is identical in both guns so that checks out ok. I also got a PM from a nice chap saying that his bar was pretty much the same as the pic I posted but it's nice to get hands on confirmation.

I was unable to strip my friend's Izzy down for a close inspection but a glaringly obvious difference was the spring tension on the breech blocks. There's just the lightest of resistance when cocking the breech block by hand on my example but, on mate Russ' gun, there's noticeably more effort required with a definite stop to be overcome at this point -

Looks like I've got a weak spring or springs somewhere. I've already stretched the valve spring a bit but that made no difference - think I'll have a look through the odds and ends drawer and see if I can find a replacement for it.